(a) Field of the Invention
The present invention relates to a thermal transfer recording medium for carrying out print recording on a recording paper utilizing the thermal melting property of an inking layer.
(b) Description of the Prior Art
As a thermal transfer recording medium, there is known one which comprises providing a thermal melting inking layer containing coloring agents such as dyes and/or pigments, fixing agents such as waxes, and other additives on a heat resisting substrate, such as polyester film. The print recording method using the above mentioned recording medium is carried out by placing a recording paper on the surface of the thermal melting inking layer of the medium, putting a thermal head thereon from the recording medium side, and melting and transferring the corresponding portion of the inking layer onto said recording paper.
However, the thus obtained records are in danger of being forged when used for the special purposes such as checks, postage stamps and the like.
On the other hand, as a fluorescent thermal transfer recording medium, there is known one which comprises providing, on the same substrate, a thermal melting inking layer consisting of fluorescent pigments, waxes and hot-melt adhesives (see Japanese Laid Open Patent Application No. 54598/1984 Specification). In the case of this fluorescent thermal transfer recording medium, the image transfer characteristic is improved as the amount of the fluorescent pigment used is decreased, but the image density (color density) and fluorescent strength are insufficient. In case the fluorescent pigments are used in large amounts, the image density and fluorescent strength are surely increased, but a sufficient image density cannot be obtained and further, the image transfer characteristic deteriorates.